import java.util.Scanner;

public class Main1304 {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        if (n>=30){
            System.out.println(n*1.0);
        }else if (n>=20&&n<=29){
            System.out.println(n*1.2);
        }else if (n>=10&&n<=19){
            System.out.println(n*1.5);
        }else if (n<=10){
            System.out.println(n*1.8);
        }
    }
}
